Air-assisted addition of grignard reagents to olefins. A simple protocol for a three-component coupling process yielding alcohols

Silylmethyl, tertiary-alkyl, alkenyl, and aryl Grignard reagents underwent intermolecular addition to olefins, such as styrenes, conjugated dienes, and enynes under an air atmosphere to give homologated alcohols. For example, (trimethylsilyl)methylmagnesium chloride and alpha-methylstyrene in ether at room temperature under dry air directly furnished 2-phenyl-4-(trimethylsilyl)-2-butanol in good yield. As the Grignard addition to olefins under argon with rigorous exclusion of O2 did not proceed at all, the above reaction should involve a radical mechanism: an alkyl radical generated by the aerial oxidation of the Grignard reagent adds to olefin, which is followed by oxygenation. Representative examples of this transformation, where products were obtained in good to excellent diastereo- or regioselectivity, are also disclosed.     

Raman scattering in low wavenumber region as a new probe to structural properties of microcrystalline silicon

The structural properties of microcrystalline silicon (μc-Si) are studied by Raman scattering. It is found that the intensity of each Raman band closely correlates with the absorption coefficient in the interband region and that the Raman band at ca. 150 cm^?1 is a sensitive probe to randomness of Si-Si bonding structure in μc-Si.     

Existence and uniqueness of stabilized propagating wave segments in wave front interaction model

Recent experimental studies of photosensitive Belousov–Zhabotinskii reaction have revealed the existence of propagating wave segments. The propagating wave segments are unstable, but can be stabilized by using a feedback control to continually adjust the excitability of the medium. Experimental studies also indicate that the locus of the size of a stabilized wave segment as a function of the excitability of the medium gives the excitability boundary for the existence of 2D wave patterns with free ends in excitable media. To study the properties of this boundary curve, we use the wave front interaction model proposed by Zykov and Showalter. This is equivalent to study a first order system of three ordinary differential equations which includes a singular nonlinearity. Using two different reduced first order systems of two ordinary differential equations, we first show the existence of wave segments for any given propagating velocity. Then the wave profiles can be classified into two types, namely, convex and non-convex types. More precisely, when the normalized propagating velocity is small, we show that the wave profile is of convex type, while the wave profile is of non-convex type when the normalized velocity is close to 1.     

Synthesis of S‐Aryl Arenethiosulfonates from N,N‐Di(arenesulfonyl)hydrazines: Reduction of Sulfonyl Chlorides with an Organic Reagent

N,N‐Di(arenesulfonyl)‐N′,N′‐dimethyl‐hydrazines, readily prepared from arenesulfonyl chlorides and N,N‐dimethylhydrazine, were heated at 120°C in chlorobenzene to give S‐aryl arenethiosulfonates, ArSSO₂Ar, in good yields.     

Study of Strangeness Photoproduction on the Neutron in the Threshold Region

Photoproduction of the neutral kaon on the deuteron has been investigated at the Research Center for Electron Photon Science, Tohoku University. We constructed the Neutral Kaon Spectrometer-2 for the detection of charged particles from the decay of the neutral kaon and the hyperon. We obtained a momentum distribution of K ⁰ with the inclusive measurement. It was consistent with the previous measurement. The total cross section of γ + d → K ⁰ + Λ + p was estimated from the measured integral cross section of γ + d → Λ + X. The total cross section with respect to the photon energy was compared with the theoretical calculations. It favored the Saclay-Lyon A model calculation with the ratio of the neutral to charged coupling constants of the axial-vector meson, K ₁, as ~ ?1.5. The energy dependence and the magnitude of the total cross section were similar to the total cross section of γ + p → K ⁺ Λ.     

Selective determination of pentoses,hexoses and 6-deoxyhexoses by dual-wavelength spectrophotometry with the cysteine—phenol—sulfuric acid system

A convenient method is described for the selective determination of pentoses, hexoses and 6-deoxyhexoses by dual-wavelength spectrophotometry with the l-cysteine—phenol—sulfuric acid system. Excellent linearity was observed for 25–250 nmol of pentoses, and for 25–500 nmol of hexoses and 6-deoxyhexoses. These aldoses in those sample ranges could be determined selectively with high accuracy and precision by the k -factor mode. The appropriate, wavelength of λ₂ was 462, 499 and 398 nm for pentoses, hexoses and 6-deoxyhexoses, respectively, whereas that of λ₁ was commonly 424 nm.     

Iron-mediated intramolecular metalative cyclization of alpha,beta-unsaturated esters and amides. Versatile one-pot preparation of bicyclic ketoesters

2-Nonen-7-ynedioic or 2-decen-8-ynedioic acid derivatives were treated with an iron reagent generated from FeCl2 and t-BuMgCl in a ratio of 1:4 to give cyclized products after hydrolysis, deuteriolysis, or the addition of carbonyl compounds. Upon reaction with the same iron reagent, 2,7-nonadienedioates afforded bicyclic ketoesters (and their enol forms) after the addition of s-BuOH or carbonyl compounds.